Journal of Oleo Science Copyright ©2018 by Japan Oil Chemists’ Society J-STAGE Advance Publication date : December 14, 2017 doi : 10.5650/jos.ess17140 J. Oleo Sci. Viscous Flow Behaviour of Karanja Oil Based Bio- lubricant Base Oil Umesh Chandra Sharma1＊ , Sadhana Sachan2 and Rakesh Kumar Trivedi3 1 University Institute of Engineering and Technology, Department of Chemical Engineering, Kanpur, Uttar Pradesh, INDIA 2 Motilal Nehru National Institute of Technology Ringgold standard institution, Department of Chemical Engineering, Allahabad, Uttar Pradesh, INDIA 3 Harcourt Butler Technological University, Department of Oil Technology, Kanpur, Uttar Pradesh, INDIA Abstract: Karanja oil (KO) is widely used for synthesis of bio-fuel karanja oil methyl ester (KOME) due to its competitive price, good energy values and environmentally friendly combustion properties. Bio-lubricant is another value added product that can be synthesized from KO via chemical modification. In this work karanja oil trimethylolpropane ester (KOTMPE) bio-lubricant was synthesized and evaluated for its viscous flow behaviour. A comparison of viscous flow behaviours of natural KO and synthesized bio-fuel KOME and bio-lubricant KOTMPE was also made. The aim of this comparison was to validate the superiority of KOTMPE bio-lubricant over its precursors KO and KOME in terms of stable viscous flow at high temperature and high shear rate conditions usually encountered in engine operations and industrial processes. The free fatty acid (FFA) content of KO was 5.76%. KOME was synthesized from KO in a two- step, acid catalyzed esterification followed by base catalyzed transesterification, process at 65℃ for 5 hours with oil-methanol ratio 1:6, catalysts H2SO4 and KOH (1 and 1.25% w/w KO, respectively). In the final step, KOTMPE was prepared from KOME via transesterification with trimethylolpropane (TMP) at 150℃ for 3 hours with KOME-TMP ratio 4:1 and H2SO4 (2% w/w KOME) as catalyst. The viscosity versus temperature studies were made at 0–80℃ temperatures in shear rate ranges of 10–1000 s–1 using a Discovery Hybrid Rheometer, model HR–3 (TA instruments, USA). The study found that viscosities of all three samples decreased with increase in temperature, though KOTMPE was able to maintain a good enough viscosity at elevated temperatures due to chemical modifications in its molecular structure. The viscosity index (VI) value for KOTMPE was 206.72. The study confirmed that the synthesized bio-lubricant KOTMPE can be used at high temperatures as a good lubricant, though some additives may be required to improve properties other than viscosity. Key words: karanja oil, karanja oil methyl ester, karanja oil trimethylolpropane ester, transesterification, bio-lubricant 1 INTRODUCTION plication as bio-lubricants include canola oil3）, castor oil4）, The conventional petroleum lubricants are marred with coconut oil5）, corn oil3）, cotton seed oil6）, jatropha curcas limitations of depleting crude oil reserves, fluctuating oil oil7）, karanja（pongamia pinnata）oil8）, mustard oil9）, palm prices, lack of biodegradability and adverse effects on oil10）, peanut oil3）, rapeseed oil11）, rice bran oil12）, safflower health, safety and environment1, 2）. Vegetable oils based oil3）, soybean oil13）, sunflower oil14）, and waste cooking bio-lubricants have emerged as a substitute for petroleum oil15）. Several of these oils are edible in nature and serve as lubricants on account of their environmentally benign key source of nutrition for 7.4 billion world human popula- properties. A number of vegetable oils in different forms tion. Lately, the research has been shifted to non-edible such as natural oil without chemical modification or sources such as karanja, linseed, rubber seed, tobacco, blended with mineral lubricating oil base stocks or addi- waste cooking oil16）, algae oil and microalgae17）, lard, tallow tives or with chemical modification via esterification, trans- and poultry fat. However, the availability of non-edible oils esterification, epoxidation, and hydrolysis have been in sufficient quantities to meet the demands of bio-lubri- applied by researchers with varying degrees of success. cant industry may be a critical issue of concern. The partial list of vegetable oils analyzed for potential ap- The elementary function of lubricating oil is to build and ＊Correspondence to: Umesh Chandra Sharma, University Institute of Engineering and Technology, Department of Chemical Engineering, Kanpur, Uttar Pradesh, INDIA E-mail: [email protected] Accepted August 30, 2017 (received for review June 21, 2017) Journal of Oleo Science ISSN 1345-8957 print / ISSN 1347-3352 online http://www.jstage.jst.go.jp/browse/jos/ http://mc.manusriptcentral.com/jjocs 1 U. C. Sharma, S. Sachan and R. K. Trivedi retain a lubrication layer between two moving metal sur- during preparation and processing of lubricant. The syn- faces to prevent their direct contact and thus reduce fric- thesis of a bio-lubricant usually requires mixing of reaction tion and wear between them1）. This function is chiefly de- components by mechanical agitation. The oil viscosity pendent on viscosity and therefore makes it the most bears a direct effect on power consumption, rotational important characteristic for selection and application of lu- speed, time of mixing, and on heat and mass transfer coef- bricating oils. A wide set of temperature and shear rate pa- ficients in esterification and transesterification process- rameters for rheological studies of lubricants have been re- es25）. ported by researchers working on mineral and/or renewable ecological lubricants（Table 1）. The test param- eters for the present study were determined by careful ex- amination of these studies. 2 EXPERIMENTAL PROCEDURES In this work, the authors have synthesized karanja oil 2.1 Materials based bio-lubricant base stock via esterification/transester- KO was obtained from Kanakdhara Agro Industries, ification route for potential application as a biodegradable Jaipur（India）. The average fatty acid composition of and environmentally friendly lubricating substitute to con- karanja oil（average molar mass 886.71 g/mol）was oleic acid ventional mineral oil lubricants. The effects of temperature 49.4％, linoleic acid 19.0％, palmitic acid 10.6％, stearic on the viscosity of the synthesized KOTMPE base stock acid 6.8％, behenic acid 5.3％, arachidic acid 4.1％, ligno- were determined and compared with that of KO and KOME ceric acid 2.4％ and others 2.4％. TMP（molar mass 134.17 at same conditions for their potential application in differ- g/mol）was obtained from Sigma-Aldrich Chemie GmbH ent lubricant formulations. （Germany）, while ethanol absolute was purchased from The current study on viscous flow behaviour of synthe- Merck, Germany. Methanol GR and anhydrous sodium sul- sized KOTMPE bio-lubricant is required to approve its ap- phate were from Merck specialities pvt. limited, Mumbai. plication in engines or in other industrial situations with Sulphuric acid abt. 98％ LR was from S. d. fine-chem satisfactory performance. A lubricant should be able to limited, Mumbai. Potassium hydroxide pellets LR were retain a normal viscosity at extreme operating conditions procured from Rankem, Ankleshwar. All chemicals were in order to prevent the moving engine/machine compo- used as it is without further purification. nents from friction and wear. Apart from application stage, the viscous flow behaviour also plays an important role Table 1 Parameters applied for rheological studies of mineral and bio-lubricants. Test Fluid Temperature Shear rate Viscosity range Equipment Reference Soybean, sunflower, high oleic sunflower 25 to 120℃ 5 to 1000 s－1 0.0544–0.0056 Pa.s (SOY) Rheometric controlled-strain 18) and castor oils with ethylene-vinyl acetate 0.0583–0.0053 Pa.s (SO) rheometer copolymer 0.0650–0.0064 Pa.s (HOSO) 0.52–0.0113 Pa.s (CO) Waste cooking oil methyl ester epoxide 28 to 100℃ 0 to 500 s－1 ≈ 23–4 cSt Anton-Paar rheometer 19) Castor oil-based ionic liquid microemulsions 0 to 100℃ － ≈ 780–20 mm2/s NDJ-5S viscometer 20) Soybean oil based bio-lubricant 30 to 80℃ － ≈ 39–9 mPa.s Brookfield controlled-stress 21) rheometer and ultra rheometer Cottonseed, soybean, groundnut and castor oils 30 to 80℃ － 75.73–24.28 s (CSO) Redwood viscometer no. 1 22) and their blends 78.83–26.28 s (SOY) 81.92–22.21 s (GO) 609.22–89.67 s (CO) DXT III, MG 20W-50, MC 20W-50, EP 90 and 20 to 50℃ 10 to 100 s－1 0.24–0.06 Pa.s (DXT III) Anton-Paar rheometer 23) SAE 20W-50 0.45–0.22 Pa.s (MG 20W-50) 0.46–0.15 Pa.s (MC 20W-50) 0.51–0.23 Pa.s (EP 90) 0.61–0.20 Pa.s (SAE 20W-50) Castor, rapeseed, soybean, sunflower and high -40 to 25℃ 10 s－1 ~ 103–100 Pa.s (CO) TA controlled-strain rheometer 24) oleic sunflower oils with viscosity modifier ~ 4–0.05 Pa.s (RO) and pour point depressant additives ~ 40–0.04 Pa.s (SO) ~ 10–0.05 Pa.s (HOSO) Engine oils SAE 15W-40, SAE 20W-40, SAE -10 to 70℃ 3 to 60 rpm 1250–32 mPa.s (SAE 15W-40) Brookfield viscometer 25) 20W-50 and SAE 25W-50 2750–40 mPa.s (SAE 20W-40) 2250–180 mPa.s (SAE 20W-50) 4250–60 mPa.s (SAE 25W-50) 2 J. Oleo Sci. Viscous Flow Behaviour of Karanja Oil Based Bio-lubricant Base Oil 2.2 Apparatus has reduced to 2 mg KOH/g oil or less. The reaction was The synthesis of KOME was done in a batch type three- carried out at conditions similar to previous step except for necked round bottom glass flask of 2 L capacity. The centre replacement of acid catalyst with base catalyst. 0.5 mol neck was equipped with a reflux condenser to reflux the （521.81 g）pretreated oil was transferred into flask and alcohol vapours back to the flask to prevent any reactant heated.